#include <string.h>
#include <stdio.h>
#include "stack.h"
#include "bintree.h"

static StackNode *stack;
static TreeNode *tree = NULL;
// TODO: binären Suchbaum implementieren
/*  * `addToTree`: fügt ein neues Element in den Baum ein (rekursiv),
 * `clearTree`: gibt den gesamten Baum frei (rekursiv),
 * `treeSize`: zählt die Knoten im Baum (rekursiv),
 * `nextTreeData`: Traversierung mit Hilfe des zuvor implementierten Stacks. */

// Adds a copy of data's pointer destination to the tree using compareFct for ordering. Accepts duplicates
// if isDuplicate is NULL, otherwise ignores duplicates and sets isDuplicate to 1 (or to 0 if a new entry is added).
TreeNode *addToTree(TreeNode *root, const void *data, size_t dataSize, CompareFctType compareFct, int *isDuplicate)
{
    if (root == NULL)
    {
        TreeNode *newNode = malloc(sizeof(TreeNode));
        newNode->data = malloc(dataSize);
        memcpy(newNode->data, data, dataSize);
        newNode->left = NULL;
        newNode->right = NULL;
        return newNode;
    }
    
    int cmp = compareFct(root->data, data);
    if (cmp < 0)
    {
        root->left = addToTree(root->left, data, dataSize, compareFct, isDuplicate);
    }
    else if (cmp > 0)
    {
        root->right = addToTree(root->right, data, dataSize, compareFct, isDuplicate);
    }
    else
    {
        if (isDuplicate != NULL)
        {
            *isDuplicate = 1; // Mark as duplicate if needed.
        }
    }

    return root;
}

// Iterates over the tree given by root. Follows the usage of strtok. If tree is NULL, the next entry of the last tree given is returned in ordering direction.
// Use your implementation of a stack to organize the iterator. Push the root node and all left nodes first. On returning the next element,
// push the top node and push all its left nodes.
void *nextTreeData(TreeNode *root)
{
    if (root != NULL)
    {
        clearStack(stack);
        buildStack(root);
    }

    if(stack != NULL)
    {
        
        void* data = top(stack);
        stack = pop(stack);
        return data;
    }

    return NULL;

}

// Releases all memory resources (including data copies).
void clearTree(TreeNode *root)
{
    if (root == NULL)
    {
        return;
    }

    if (root->left != NULL)
    {
        clearTree(root->left);
        free(root->left);
        root->left = NULL;
    }
    if (root->right != NULL)
    {
        clearTree(root->right);
        free(root->right);
        root->right = NULL;
    }
    root = NULL;
}

// Returns the number of entries in the tree given by root.
unsigned int treeSize(const TreeNode *root)
{
    return root == NULL ? 0 : treeSize(root->left) + treeSize(root->right) + 1;
}

void buildStack(TreeNode *root)
{
    
    if (root == NULL)
    {
       return; 
    }
        
    buildStack(root->left);   // biggest first
    stack = push(stack, root->data);                 // push
    buildStack(root->right); 
}